Here’s how subtle a hiring bias can be.

Lynn Bartels showed 542 participants a resume and a photograph of hypothetical applicants. The resumes were the same, but the pictures differed. There were four choices: a man and a woman of average weight and a man and a women who were overweight.

Bartels, an associate professor of psychology at Southern Illinois University, found a clear difference in how the “hirers” evaluated the job candidates.

The overweight woman routinely was channeled to a job less visible to the public.

“When men are heavy, they can be perceived as more athletic, but there are societal differences in terms of the pressures put on women,” Bartels said.

Thus, heavy women may need to work harder to counter stereotypes of being lazy or unhealthy, she said.

But that doesn’t mean fat men have it much easier in the job market.

Bartels’ study affirms research that has found a “beauty bias,” a workplace discrimination against fat people – male or female – or those perceived as unattractive.

That kind of bias has no legal prohibition.

“People can be very upfront about saying, ‘I wouldn’t hire a fat person,’ ” she said.

As long as employers avoid discrimination based on age, sex, race, religion and any other legally protected category, employers can hire people who fit any image they want their workforce to present.

It’s important for overweight job applicants to understand that an obesity bias may exist. That may require working harder to give the impression of energy and good health.